The invention relates to a door actuation arrangement with sensor means for detecting the approaching movement of a user. In particular the invention relates to door handle systems with capacitive proximity sensors.
Such capacitive sensor systems are well known in technology and can detect the approaching movement of a user in a non-contacting manner. To this end the change of the capacity of an electrode arrangement is measured, which among other things is dependent on the proximity of the body part of a user. An exemplary arrangement can be learned from DE102005061755A1.
Such sensor systems are used in the state of the art for “passive entry” systems, in which case the user no longer needs to actively actuate a button of a radio remote control for access to a vehicle. Instead, it is sufficient that the user carries the designated radio remote control as an ID transmitter (identification transmitter) on his person (for example, in a pocket of the clothing or briefcase). In this connection, the proximity of the user to the door of the motor vehicle is detected by means of a proximity sensor, whereupon a controller arranged in the motor vehicle sends a radio signal via a transmitting antenna (for example arranged in a door handle) to the ID transmitter located on the person of the user, that the ID transmitter should “wake up”. Upon receipt of the wake-up signal a radio dialog begins between the ID transmitter and the controller of the motor vehicle, in whose result the authorization or non-authorization of the ID transmitter is established. If the authorization of the ID transmitter is established, the door lock is unlocked, so that the door lock can be opened by a subsequent actuation of the door handle. For example, one of the mentioned capacitive sensors is used as an approximation sensor.
In other respects, it is known that such sensor arrangements are dependent on the weather and dependent on other environmental conditions. The humidity, precipitation and other influences likewise change the capacity of the sensor system.
In the case of the use of a capacitive sensor for detection of the approaching movement of a user, it is therefore problematic to establish without a doubt the approaching movement of an operator body part, for example, a hand to the door handle for the purpose of opening the door in the event of such disturbing influences.
Door handle systems in which capacitive proximity sensors are integrated that are protected from environmental influences are known in the prior art. For example, EP 03 100 728.9 discloses a system which arranges a capacitive sensor arrangement behind a housing wall. The space between the sensor arrangement and the housing wall is filled with an electrically insulating material in order to prevent the entry of moisture or other foreign substances.
In particular, the influence of disturbing effects in the proximity of the electrodes of a capacitive sensor is to be prevented at all costs. Capacitive sensors can therefore be embedded in particular in sealing compounds in order to prevent a direct influence of the sensor surfaces. The above prior art in addition fills the entire space between such a cast electrode arrangement and a wall of a door handle with insulating material.
However, the disadvantage of the system is the fact that the influence of this material, even if it deters even more damaging influences from the detection range, is detrimental to the detection sensitivity. Even if the material is an electrically insulating material, it is nevertheless a dielectric influencing the capacity.
In other respects, the handle arrangement is subject to drastically changing environmental conditions and environmental temperatures, so that in the case of the solutions according to the prior art, due to changes in size gaps occur on a regular basis, said gaps into which substances can still penetrate or in which a condensation of fluid takes place.
The problem addressed by the invention is that of providing a fluid- and condensation-independent sensor device that has improved detection sensitivity.